Electrical connector

ABSTRACT

An electrical connector for connecting a plurality of electrical load circuits to an electrical distribution loop via a removable element, such as a current limiting fuse. The connector includes a housing formed of an insulating resin system, including a chamber in which the removable element is disposed. First and second spaced contacts are carried by the housing which cooperate with first and second spaced electrodes carried by the removable element, to interconnect the first and second spaced contacts via the removable element. The housing defines first and second integral, tubular outward projections in which contacts are disposed which are connected to the first contact, and a plurality of additional integral, tubular outward projections in which contacts are disposed which are connected to the second contact. The first and second tubular projections are adapted to removably receive and electrically interconnect first and second electrical cables, respectively, in the electrical distribution loop, and the plurality of additional tubular projections are adapted to removably receive electrical cables connected to load circuits. Arc extinguishing members are carried by the housing and by the removable member, to make the assembly and disassembly of the connector load-make and load-break at the contact connected to the electrical distribution loop.

United States Patent Keto et al.

[45] Oct. 10, 1972 [54] ELECTRICAL CONNECTOR [72] Inventors: August I. Keto, Sharon; James R.

Farley, Pittsburgh, both of Pa.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: March 29, 1971 21 Appl.No.: 128,729

[52] US. Cl ..339/111, 174/72 R [51] Int. Cl. ..H01r 13/68 [58] Field Of Search ..339/l47, 111, 213, 242, 94;

Primary ExaminerRichard E. Moore Atl0rneyA. T. Stratton, F. E. Browder and Donald R. Lackey [57] ABSTRACT An electrical connector for connecting a plurality of ala /ale ale fella RESIDENCE electrical load circuits to an electrical distribution loop via a removable element, such as a current limiting fuse. The connector includes a housing formed of an insulating resin system, including a chamber in which the removable element is disposed. First and second spaced contacts are carried by the housing which cooperate with first and second spaced electrodes carried by the removable element, to interconnect the first and second spaced contacts via the removable element. The housing defines first and second integral, tubular outward projections in which contacts are disposed which are connected to the first contact, and a plurality of additional integral, tubular outward projections in which contacts are disposed which are connected to the second contact. The first and second tubular projections are adapted to removably receive and electrically interconnect first and second electrical cables, respectively, in the electrical distribution loop, and the plurality of additional tubular projections are adapted to removably receive electrical cables connected to load circuits. Arc extinguishing members are carried by the housing and by the removable member, to make the assembly and disassembly of the connector load-make and load-break at the contact connected to the electrical distribution loop.

14 Claims, 11 Drawing Figures RESIDENCE PATENTED 10 I97? 7 3,697,932

sum 3 0F 4 FIG.2A.

ELECTRICAL CONNECTOR BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates in general to electrical connectors, and more specifically to load-make, load-break connectors for connecting a plurality of electrical circuits to an electrical distribution loop.

2. Description of the Prior Art The primary and secondary distribution systems of electrical utilities have been primarily of the overhead type, with the most common circuit arrangement being the radial system. Underground distribution of electrical power has been increasing in recent years due to the increasing number of new subdivisions resorting to underground distribution of electrical power for esthetic reasons. Underground residential distribution systems are inherently more costly than distribution systems of the overhead type, and their cost is further increased because they utilize the more reliable loop system. The cost of the loop system is further increased, compared with the overhead system, when a small distribution transformer is specified for each residence, or for two adjacent residences. In this instance, the underground shielded cable, which is buried near the curb line, loops into each of the distribution transformers, crossing a front yard twice for each transformer, as each transformer is located adjacent to the residence, or residences, it serves. This arrangement requires two high voltage splices and two stress cones at each transformer, two high voltage bushings on each transformer, and two runs of high voltage shielded cable between the street and location of the transformer adjacent the residence, or residences.

The cost of the underground distribution system could be substantially reduced by using a loop-radial circuit arrangement, wherein the primary circuit loops through a subdivision of houses along the curb line, with laterals or radials being tapped off the loop for each transformer. Thus, only one run of high voltage shielded cable is required between the loop system and the distribution transformer, and distribution transformers with a single high voltage bushing may be utilized. The success of this arrangement, however, depends upon providing a low cost connector for tapping the radial feeders into the loop cables, quickly and efficiently, while making a reliable, moisture-proof, low stress connection.

Underground residential distribution systems which utilize a distribution transformer disposed immediately adjacent to the residence, or residences, it serves, also present the problem of protecting the loop system against faults in the connected high voltage cable and transformers. For example, the loop system should be protected from faults in the connected high voltage cable due to dig-ins which may occur in the front yard of a residential user. Thus, in addition to providing a low cost connector for tapping a radial feeder into a shielded cable which is part of a loop distribution feed system, it would also be desirable to provide some means for protecting the loop system from faults in the high voltage radial feeder cable and distribution transformers.

Co-pending application Ser. No. 798,294, filed Feb. ll, 1969, now US. pat. No. 3,602,872 issued Aug. 31, 197], which is assigned to the same assignee as the present application, discloses a connector suitable for such applications. it would be desirable, however, to make the insertion and removal of the load circuits to the radial loop load-make and load-break, respectively, and to also provide a new and improved housing and cable connection arrangement for the electrical connector which facilitates the manufacture and assembly thereof, without sacrificing reliability and other essential features of such a connector.

SUMMARY OF THE INVENTION Briefly, the present invention is a new and improved electrical connector for connecting a plurality of electrical load circuits to an electrical distribution loop via a removable element, such as a current limiting fuse. The connector includes an insulating housing formed of a resin system which not only defines a chamber for receiving the removable element, but also forms integral tubular projections which form plug-in receptacles for receiving suitably prepared ends of the high voltage cable in the loop distribution system, and similarly prepared ends of the high voltage cable in the plurality of load circuits connected to the loop system via the removable element.

First and second spaced contact means are partially embedded in the insulating housing, with portions thereof accessible within the chamber for receiving the removable portion and engaging its contacts. Portions of each of the first and second spaced contact means are also accessible at the inner ends of different tubular projections, providing contact members for making electrical contact with the high voltage cables, when the high voltage cables are plugged into the tubular projections.

A resilient, electrically conductive tubular member or boot is disposed in each of the integral tubular projections of the housing, with the outer surface of each boot being bonded to the inside wall of its associated tubular member, and with the contact member of the tubular projection being disposed within the opening of the electrically conductive boot.

The high voltage cable of the electrical distribution loop may thus be cut at any point at which it is desired to connect load circuits thereto, with the resulting two ends of the cable being suitably prepared and plugged into predetermined tubular projections on the insulating housing, which reestablishes the continuity of the electrical distribution loop through the first contact means. The high voltage cable of the laterals or load circuits to be connected to the electrical distribution loop are also suitably prepared and plugged into tubular projections in which contact members associated with the second contact means are disposed. Assembly of the removable member in the chamber of housing bridges the first and second contact means, connecting the electrical distribution loop to the load circuits via the removable element. The removable element has first and second contacts or electrodes which engage the first and second contact means of the housing, respectively, with cooperative arc extinguishing members being provided for the removable element and for the housing, which members make the assembly and disassembly of the removable element load-make and load-break, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be better understood, and further advantages and uses thereof more readily apparent, when considered in view of the following detailed description of exemplary embodiments, taken with the accompanying drawings, in which:

FIG. I is a schematic diagram of an electrical distribution loop which may advantageously utilize electrical connectors constructed according to the teachings of the invention;

FIG. 2 is an elevational view, partially in section, of an electrical connector constructed according to the teachings of the invention;

FIG. 2A is a perspective view of the insulating housing portion of the electrical connector shown in FIG. 2;

FIG. 3 is a sectional view of the connector shown in FIG. 2, taken along the lines III-III;

FIG. 4 is a sectional view of the connector shown in FIG. 2, taken along the lines IV-IV;

FIG. 5 is a fragmentary elevational view of the connector shown in FIG. 2, taken in the direction of arrows V-V',

FIG. 6 is a sectional view of a composite resilient member which surrounds each high voltage cable when the cable is assembled with the connector shown in FIG. 2;

FIG. 7 is an elevational view, partially in section, of the removable element of the connector shown in FIG.

FIG. 7A is a fragmentary view of the removable element shown in FIG. 7, except modified to include fuse elements of smaller ratings;

FIG. 8 is a elevational view, partially in section, of another removable element which may be used with the connector shown in FIG. 2, when it is desired to use the connector as a sectionalizing switch; and

FIG. 9 is an elevational view, partially in section, of still another removable element which may be used with the connector shown in FIG. 2, when it is desired to ground the load circuit during maintenance thereof.

DESCRIPTION OF PREFERRED EMBODIMENTS generally by conductor 10, and a single-phase electrical distribution loop 12 connected to the three-phase system via switches 14 and 16. The single-phase distribution loop, which may be underground, and at a distribution voltage level of the 15 KV class, or any other distribution voltage level, includes a sectionalizing switch 18, which is connected to the loop 12 at about its midpoint, and a plurality of electrical connector switches 20, 22, 24 and 26. Each of the electrical connector switches connect a plurality of electrical load circuits to the electrical distribution loop 12 via a connecting element, such as a current limiting fuse, with each load circuit including a distribution loop 12 via a connecting element, such as a current limiting fuse, with each load circuit including a distribution transformer which serves one or more residences. For example, connector switch 22 includes a fused removable element 28, and four load circuits 30, 32, 34 and 36. Each of the load circuits are connected to a distribution transformer, such as distribution transformer 38, which is shown connected to load circuit 36, with the transformer 38 being connected to one or more residences, such as residence 40. The electrical connector switches 20, 22, 24 and 26, as well as the sectionalizer switch 18, may all be constructed according to the teachings of the invention, and they are illustrated as having plug-in type connections, as taught by the invention. For example, electrical connector 22 is illustrated as having first and second plug-in connectors 42 and 44, to which the high voltage cable of the electrical distribution loop 12 is connected, and plug-in connectors 46, 48, 50 and 52, to which the high voltage cables of the load circuits 30, 32, 34 and 36 are respectively connected.

FIG. 2 is an elevational view, partially in section, of an electrical connector 60 constructed according to the teachings of the invention. Connector 60, which may be used for the electrical connectors shown in FIG. 1, underground, above grade, vault mounted, or in any other suitable arrangement, includes a fixed receptacle 62 and a removable connecting element 64. The fixed receptacle 62, which is shown in perspective in FIG. 2A, includes a housing 66 formed of a cast insulating resin system, such as the filled epoxy resin system disclosed in US. Pat. No. 3,547,871, which is assigned to the same assignee as the present application. However, any other suitable insulating resin system may be used which is weather resistant, and which possesses the requisite electrical and mechanical strengths. The fillers for the resin system should be selected to closely match the coefficient of thermal expansion of the resulting resin system with that of metallic inserts embedded therein, such as copper or aluminum contacts, which embedments will be hereinafter described. Finely divided quartz flour, lithium aluminum silicate, beryllium aluminum silicate, and alumina trihydrate are examples of suitable fillers, with the latter being used in combination with other fillers when arc and track resistance is required.

The insulating housing 66 includes a generally cylindrical main body portion 68 having first and second ends 69 and 71, respectively, with the main body portion 68 defining an elongated chamber 70 having first and second ends 72 and 74 which are open and closed, respectively. The insulating housing 66 also includes first and second substantially tubular portions 76 and 78, which are integrally formed with the main body portion 68, with the tubular portions 76 and 78 extending perpendicularly outward in opposite directions from the main body portion 68, near the closed or blind second end 74 of the chamber 70. Tubular portions 76 and 78 are also shown in FIG. 4, which is a cross-sectional view of insulating housing 66 taken along the line IV-IV.

A plurality of additional substantially tubular portions 82, 84, 86 and 88 are also integrally formed with the main body portion 68, with the tubular portions 82 and 84 extending perpendicularly outward from one side of the main body portion 68, in spaced, parallel relation with one another, and with tubular portions 86 and 88 extending perpendicularly outward from the other side of the main body portion 68, in spaced parallel relation with one another, with the centerlines of the tubular projections 82 and 86 being in alignment, and with the centerlines of the tubular projections 84 and 88 being in alignment. Tubular portions 82, 84, 86 and 88 are also shown in FIG. 3, which is a cross-sectional view of the insulating housing 66 taken along the line lll'-l1l.

Each of the outwardly extending tubular portions 76, 78, 82, 84, 86 and 88 define an opening or recess having an inner closed end and an outer open end, such as the recess 90 in tubular portion 86, which has a closed inner end 92 and an open outer end 94.

First and second spaced contact means 96 and 98, respectively, are carried by the insulating housing 66, with portions thereof embedded in the cast resin system of the main body portion.

The first contact means 96 includes a substantially U-shaped conductor 100, which is formed of copper, aluminum or other good electrical conductor, with the U-shaped conductor 100 having first and second spaced parallel leg portions 102 and 104, respectively, which are interconnected by bight 106. First, second and third contact members 108, 110 and 112, respectively, are all connected to the U-shaped conductor 100. The first contact member 108 may be threadably secured to the bight 106 by a pin 114 which extends perpendicularly through an opening in the bight 106, with the contact member 108 extending outwardly from the bight 106 in parallel relation with, and between the spaced leg portions 102 and 104 of the first contact means 96. The second and third contact members 110 and 112, which are elongated pin-like members, are fixed to legs 102 and 104, respectively, of the U-shaped conductor 100, extending perpendicularly outward from the outermost sides of the legs 102 and 104, near their extreme ends. The longitudinal centerlines of the contact members 110 and 112 are substantially coaxial.

The U-shaped conductor 100 of the first contact means 96 is completely embedded in the cast solid resin system of the main body portion 68 of the housing 66, such that pin 114 has one end embedded in the cast resin system, and a threaded end which extends coaxially into chamber 70 through the closed end 74 of the chamber, enabling the first contact member 108 to be removably fastened to pin 114 by inserting the first contact member 108 into the chamber 70 and threadably engaging it with the pin 114, using a suitably designed tool.

The second and third contact members 110 and 112 may be partially embedded in the cast resin system, adjacent their ends which are connected to the first and second legs 102 and 104, respectively, of the U-shaped conductor 100, with the extreme outer ends of the contact members 110 and 112 extending coaxially into the recesses defined by the integral tubular extensions 78 and 76, respectively, through the blind or closed ends of the recesses.

First and second resilient, electrically conductive tubular members or boots 116 and 118 are disposed to surround the portions of the second and third contact members 110 and 112, respectively, which extend into the recesses defined by the tubular extensions 78 and 76. The resilient boots 116 and 118 may, for example, be formed of an electrically conductive rubber. Each of the resilient boots have first and second ends, such as first and second ends 120 and 122, respectively, on boot 118, with a small opening being provided through the first end of the boot for snugly receiving the associated contact member which extends into the recess of the tubular projection, and a larger opening at its second end. The inside surface of each of the electrically conductive boots has a circumferential groove disposed adjacent to but uniformly spaced from the second end of the boot by a predetermined dimension, such as the circumferential groove 124 in boot 118.

The outer surfaces of the electrically conductive boots 116 and 118 are bonded to the resin system of the main body portion 68 of housing 66, with it being convenient to dispose the boots over their associated contact members, and cast the boots in this position when the main body portion 68 is cast. in other words, the first contact means 96, with the electrically conductive boots 116 and 118 in position about conductive members and 112, may be placed as an assembly within the mold prior to introducing the resin system therein. Wire brushing the external surfaces of the boots 116 and 118 will promote excellent adhesion between the cast resin system and the outer surfaces of the boots, insuring that there will be no air trapped in the interface between the boots and resin system which may ionize during the usage of the electrical connector 60. The electrically conductive boots 116 and 118 will be at substantially the same electrical potential as the first contact means 96, when the first contact means 96 is energized, reducing the potential gradient between the contact members and the inner surfaces of their respective boots, to substantially zero. This arrangement increases the effective radii of the contact members 110 and 112 to that of the outer surfaces of their associated boots. The potential gradient at the outer surface of each of the boots is thus substantially less than that which would occur at the surface of the conductive members 110 and 112 in the absence of a boot. Then, the fact that there is no air at the interface of the boot and cast resin insulating system, further reduces the chance of corona formation, as the cast resin system has a higher electrical breakdown strength than air.

The first contact means 96 is completed by an insulating sleeve or tube 119 formed of a suitable arc extinguishing material. Insulating sleeve member 119 is constructed to surround contact member 108, and it includes an opening which is coaxially aligned with the opening in contact member 108, through which the contact of the removable member 64 proceeds just prior to its engaging contact member 108. Insulating sleeve 119 cooperates with an insulating probe or rod formed of arc extinguishing material which is carried by the removable portion 64, as will be hereinafter explained, to provide the desired load-break capability for the electrical connector 60, with the term loadbreak capability" also including load-make and fault close-in capabilities.

The second contact means 98 includes a metallic, tubular, cylindrical contact member 126, which is formed of aluminum or copper, and which has an opening 128. First and second elongated, rod-like, electrically conductive contact members and 132, which are also formed of aluminum or copper, are fixed in spaced parallel relation with one another to opposite points on the curved outer surface of the tubular contact member 126, perpendicular to the axis of opening 128.

The second contact means 98 is partially embedded in the cast resin system of the main body portion 68 of housing 66. The second contact means 98 is axially spaced, along chamber 70, from the first contact means 96, with the opening 128 in its tubular contact member 126 being coaxial with the longitudinal axis of chamber 70. The inner surface 133 of the tubular contact member 126 is accessible from within chamber 70. The chamber 70 may have a substantially uniform diameter from its closed end 74 to the uppermost end of the tubular contact member 126, which diameter is substantially the same as the inside diameter of the tubular contact member 126, and then chamber 70 may taper slightly outward, such as indicated at 134, with the taper terminating at a slightly larger inside diameter, which may be uniformly maintained from the end of the taper 134 to the open end 72 of the chamber 70.

Each of the electrically conductive contact members 130 and 132 have first and second ends, with each of their ends functioning as an electrical contact. The first and second electrically conductive contact members 130 and 132 are oriented, when the main body portion 68 of housing 66 is cast, such that their outwardly extending ends extend coaxially into the recesses defined by the tubular extensions, through the inner or closed ends of the recesses. For example, the first and second ends of the first contact member 130 extend into the recesses defined by tubular extensions 82 and 86, respectively, and the first and second ends of the second contact member 132 extend into the recesses defined by the tubular extension 84 and 88, respectively.

Electrically conductive rubber boots 136, 138, 140 and 142 are disposed within the recesses defined by tubular extensions 82, 84, 88 and 86, respectively, about the ends of the contact members 130 and 132 which extend into the recesses, with the electrically conductive boots being constructed and placed relative to their associated contacts and tubular extensions of main body portion 68, as hereinbefore described relative to the electrically conductive boots 116 and 118.

A metallic hasp 150, having a slot-like opening 152 therein, is pivotally mounted to the first end 69 of the insulating housing 66, such as by embedding a tapped metallic insert 154 into the first end of the insulating housing, to which the hasp 150 may be threadably secured by a suitable fastener. A hinge 156 enables the hasp 150 to pivot and secure the removable element 64 in assembled relation with the insulating housing 66, as will be hereinafter described.

The insulating housing 66 is threaded on its external surface, as illustrated at 144, starting near its first end 69, which threads cooperate with a tubular metallic extension or housing 146, to make the electrical connector 60 accessible from above the grade or ground level 148, as will be hereinafter explained.

The insulating housing 66 has an electrically conductive coating 158 disposed uniformly over its external surface, as indicated within circle 160, which circle in dicates a magnified view of the outer surface of housing 66. The electrically conductive coating 158 may be an electrically conductive paint, such as an aluminum paint, which is brushed, sprayed, or otherwise uniformly applied to the outer surface of housing 66.

Housing 66 is completed by fastening a metallic angle 162 to its external surface, in contact with the electrically conductive coating 158, such as by inserting bolts 164 and 166 through openings disposed in one side of the metallic angle 162, which bolts threadably engage tapped metallic inserts embedded in the cast resin of which the housing 66 is formed. FIG. 5 is a fragmentary elevational view of housing 66, taken in the direction of arrows V-V, which illustrates the location of the metallic angle 162, and the metallic angle 162 is also shown in FIGS. 2A and 4. A plurality of openings 168 are disposed through the remaining side of the metallic angle 162 for receiving fasteners which connect a ground rod and the wire strapping of shielded cables to the metallic angle 162.

The shielded cables of the electrical distribution loop and of the various load circuits may be quickly prepared in the field for plug-in connection with the contacts disposed in the insulating housing 66. As illustrated in FIGS. 2, 3 and 4, shielded cables 170 and 172 are from the electrical distribution loop, and their ends are plugged into the recesses defined by the tubular extensions 78 and 76, respectively, to reestablish the electrical continuity of the electrical distribution loop, and to energize the contact element 108. Shielded cables 176, 178 and 180 cooperate with tubular extensions 82, 84 and 88, respectively, to energize their respective load circuits via the removable connecting element 64. A similar shielded cable (not shown) would be plugged into the recess defined by tubular extension 86.

Cable 180 is shown plugged into the tubular extension 88 in FIG. 3, and unplugged in FIG. 2, in order to better illustrate its construction, and since each cable is prepared in a similar manner, only the preparation and construction of the end of cable 180 will be described in detail.

The first step in preparing the end of cable 180 is to remove the cable insulation and shield from the end of the cable, exposing a predetermined length of the stranded or solid conductor 182 of the cable, and a female or socket terminal 184 is then crimped onto the bared conductor 182, such that the socket terminal 184 is butted up against the cable insulation at 186. Socket terminal 184 has an opening 186 at its other end which cooperates with the male contact member disposed in the recess of the tubular extension 88, expanding slightly when it is coupled with the male contact member to provide and maintain good electrical contact between the engaging contacts. The semiconductive cable shield 188 is then cut back to 190, exposing the cable insulation 192 for a predetermined longitudinal dimension.

Next, a specially prepared composite resilient sleeve 194 is provided, which is shown in an enlarged crosssectional view in FIG. 6. Sleeve 194 is slipped over the end of the cable 180 prior to insertion of the cable 180 into the tubular extension of the housing 66. Resilient sleeve 194 has first and second ends 195 and 197, respectively, and it includes first and second axially connected portions 196 and 198, respectively, bonded together at 200, with the first portion 196 being formed of an electrically conductive rubber and the second portion 198 being formed of an insulating rubber. The second portion 198 has an inside diameter 202 sized to snugly receive the outside diameter of the portion of cable 180 which has only the semiconductive shield 188 removed, i.e. the portion with insulation 192 exposed, and this diameter continues into the second portion 196 of the composite sleeve for a predetermined dimension, and then the diameter increases at 206 to a larger diameter 208 sized to snugly receive the portion of cable 180 which has its semiconductive layer intact, i.e. portion 188. A circumferential ridge 210 encircles the outside diameter of portion 198, adjacent to end 197, which cooperates with a circumferential groove 212 disposed in resilient boot 140, as will be hereinafter explained. The outside diameter of the composite sleeve 194 is slightly tapered, decreasing in diameter from end 195 to end 197, which cooperates with a complementary taper on the inside diameter of the tubular extension 88, to provide a moisture-proof seal. A flange 214 may be provided on the composite sleeve, near end 195, if desired, which will butt up against the outwardly extending end of the tubular pro-- jection 88, but the flange is not essential.

Prior to telescoping the composite sleeve 194 over the end of cable 180, the inside diameter of the composite sleeve 194 and portion 192 of electrical cable 180 should be coated with a silicon grease to facilitate their assembly, and also to force air out of the assembly. Once the composite sleeve 194 is in the proper position on cable 180, the semiconductive shield layer 188 contacts the electrically conductive portion 196 of the composite sleeve 194. The cable 180 is now ready to be plugged into the recess defined by the tubular extension 88. The inside diameter of the tubular extension should be coated with silicon grease, as well as the outside diameter of insulating portion 198 of the composite sleeve 194, to facilitate their assembly and to force air out of the resulting assembly. The cable 180 is inserted into the tubular extension until the circumferential ridge 210 on the end of the composite sleeve 194 snaps into the cooperative groove 212 on the inside diameter of the electrically conductive boot 140. The conductive portion 196 of the composite sleeve 194 electrically connects the semiconductive shield layer 188 on the cable 180 to the electrically conductive coating 158 on the housing 66. The wire strapping on cable 180, indicated at 216, is twisted together and connected to the metallic angle 162, with suitable fastening means, such as a nut and bolt assembly. In like manner, the remaining ends of the cables will be prepared and plugged into their associated recesses, and their wire strappings are also twisted and connected to the metallic angle 162.

The removable element 64, shown in FIG. 2, is shown in an enlarged elevational view in FIG. 7. The removable element 64 includes a fuse 220, which is a fuse of the non-vented current limiting type. Fuses of the current limiting type are disclosed in U.S. Pat. Nos. 2,496,704, 2,502,992 and 3,134,874, for example, all of which are assigned to the same assignee as the present application. Current limiting fuse 220 includes an insulating fuse tube 222, which is formed of a suitable material such as glass melamine, first and second ferrules or electrodes 224 and 226, respectively, which may be pressed over and secured to the fuse tube 222 by a suitable adhesive, or otherwise suitably fixed to opposite ends of the fuse tube. A fusible element (not shown) is disposed through the opening in the fuse tube 222, and connected between the first and second electrodes 224 and 226. The fusible element is usually formed of a flat ribbon of silver with a plurality of spaced notches which extend inwardly from the sides thereof, periodically reducing the width of the strip and providing a series of arcs during the operation thereof, with the sum of the plurality of arc voltages providing the current limiting effect required. Arc extinction without requiring venting of the fuse is obtained by filling the fuse tube 222 with a pulverulent or granular arc quenching material, such as silica sand.

The first and second electrodes 224 and 226 have means connected thereto, such as axially extending threaded stud members 228 and 230, respectively, for connecting electrical contact members thereto. The current limiting fuse 220 provides protection for the loop distribution system against faults in cables, transformers and loads connected to the load side of the electrical connector 60, with the current limiting fuse terminating an overload or short circuit current at the designed let-through current. The current limiting fuse 220 also protects operating personnel, as the current limiting fuse may be safely connected into the circuit even when the circuit has a low impedance fault. The current limiting fuse will open a faulted circuit without exploding or otherwise initiating hazardous operating conditions.

The first electrode 224 of the fuse 220 includes a contact member 232 in the form of a garter spring, which is formed of beryllium-copper, or other suitable material, with the garter spring 232 being held in position adjacent to electrode 224 of the fuse 20 by a retaining member 234. The retaining member 234 is an electrically conductive member which is shaped similar to an inverted hat, having a generally cylindrical portion with a closed end, except for a small centrally located opening therein, and an open end, which is terminated by an outwardly extending flange 236. The opening in the closed end of the retaining member 234 accepts the stud member 228 on the electrode 224, with the flange portion 236 holding the garter spring against the electrode 224. This construction is suitable when the rating of the current limiting fuse is such that the diameter of the ferrule 224 is sufficient to support the garter spring 232. Smaller ratings of the current limiting fuse for a specified voltage would maintain the same longitudinal dimension, but the outside diameters of the fuse tube and ferrules would be reduced. When the diameter of the ferrule 224 is not sufficient to support the garter spring 232, an additional support plate may be disposed over the stud member 228, with the additional support plate having the required diameter to provide support for the garter spring 232. This embodiment of the invention is illustrated in FIG. 7A, which is a fragmentary view of the removable element 64 shown in FIG. 7, except with a smaller diameter fuse electrode, given the reference numeral 224', and including a support plate 238 which is used to provide the required support for the garter spring 232.

Referring again to FIG. 7, retaining member 234 is held in position by a ball joint or universal assembly 240, which has first and second portions 242 and 244. The first portion 244 includes a threaded stud member 246 and a socket, and the second portion 244 includes a ball disposed in the socket of the first portion, and a tapped opening 248. The stud 228 connected to the electrode 224 cooperates with the tapped opening 248 to secure the ball joint assembly 240 to the fuse 220, and also to secure the retaining member 234 securely against the electrode 224.

The stud member 246 on portion 242 is then threadably engaged with a tapped opening in one end of an insulating operating shaft member 250, which shaft may be formed of a suitable resin, such as an epoxy resin system, or a glass filled methylmethacrylate. lnsulating shaft member 250 may taper outwardly near its other end, as indicated at 252, to guide the shaft 250 as the removable element 64 is rammed into the housing 66 with a hot stick. The ball joint 240 facilitates the insertion of the fuse 220 and its operating shaft 250 into the chamber 70 of the insulating housing 66, preventing a bending moment from being applied to the fuse as the connector 66 is threaded into the first end of chamber 70.

Since connector 60 will usually be mounted below the grade level 148, or in a vault which may become flooded, it is essential that the opening to chamber 70 be sealed by the removable element 64, when the removable element 64 is assembled with the housing 66. Thus, the removable element 64 must include means for sealing the opening 72 to the chamber 70 adjacent the first end 69 of the housing 66. The sealing means may be in the form of a stopper or seal 254, which is formed of a resilient material, such as rubber, with the stopper or seal 254 being expandable, if desired, such as by turning a metallic eye bolt 256, or by pivoting a cam operating mechanism which expands the seal. The eye bolt 256 may be disposed through an opening in the stopper 254, and threadably engage a tapped opening in the insulating operating shaft 250, enabling the removable element 64 to be handled by a hot stick inserted through the opening in the eye bolt 256.

The electrode 226 of fuse 220 includes a second contact member of fuse 220, which is a cylindrical, .elongated terminal or contact 258. Contact 258, which has an outside diameter sized to cooperate with the inside diameter of the contact member 108 fixed to the housing 66, is threadably secured to the stud member 230 depending from the ferrule or electrode 226 of the fuse 220.

A probe type insulating member 260 is carried by contact 258 at its outward end, with the outside diameter of insulating member 260 being the same as the outside diameter of contact 258. The insulating member 260 functions as a snuffer rod, cooperating with the insulating sleeve 119 carried by the housing 66 to squeeze an arc formed between the contact rod 258 and the female contact 108, between the probe or snuffer rod 260 and the sleeve 119, and extinguish the are by liberating arc-extinguishing gases.

The insulating probe 260 and sleeve 119 are both formed of arc-extinguishing materials. There are many different insulating materials which possess arc-extinguishing characteristics, as opposed to are tracking characteristics, with the arc-extinguishing materials producing gases when being subjected to the heat of an arc, which gases expand to blast, cool and deionize the arc. Further, the by-products of a good arc-extinguishing material will not track or create a path for electrical current to flow. For example, the arc-extinguishing members may be formed of a high molecular weight polyoxylmethylene, as disclosed in U.S. Pat. No. 3,059,081, which is assigned to the same assignee as the present application; or, preferably, the arc-extinguishing members may be formed of a material which includes glass fiber dispersed in a methylmethacrylate polymer, which construction is disclosed in co-pending application Ser. No. 1,827, filed Jan. 9, i970, which application is assigned to the same assignee as the present application. Arc-extinguishing members formed of glass filled methylmethacrylate interrupt and extinguish an are without excessive gas formation, and without providing excessive amounts of conductive particles, such as free carbon, which makes its use in closed type electrical connectors particularly attractive.

The longitudinal dimension of the inner surface 133 of the tubular contact member 126 is selected such that the contact 232 of the removable portion or element 64 makes contact with the tubular contact member 126 prior to the engagement of the lower contacts 258 and 108, and conversely such that upon removal of the removable element 64, contacts 258 and 108 will disengage prior to contact 232 leaving the inner surface 133 of the tubular contact member 126. This arrangement insures that the load-make and load-break functions occur at the lower contact assembly, where the arc-extinguishing members are disposed to extinguish the arc.

In the installation and operation of the electrical connector 60, connector is disposed in the trench in which the cable of the high voltage distribution loop is to be buried, in the embodiment of the invention where the connector is used with underground residential distribution systems. The cable of the high voltage distribution loop is cut and the ends prepared, as hereinbefore described. The prepared ends of the cable are then plugged into the recesses defined by the tubular extensions 76 and 78. To insure that the cables will not be pulled out when earth is placed about the electrical connector 60, a length of heat shrinkable tubing may be placed about each of the cables before they are plugged into the tubular extension, with the heat shrinkable tubing then being directed to cover the joint formed between the cable and tubular extension. Heating the heat shrinkable tubing will shrink it tightly about the joint, preventing the cable from being accidentally pulled out of contact or engagement with the housing 66. FIGS. 2 and 4 indicate a length of heat shrinkable tubing 262 in place about the joint between the cable 172 and tubular extension 76.

The cables for the various load circuits may be similarly prepared and plugged into the tubular extensions 82, 84, 96 and 88, and they may also be secured in assembled relation with the housing 66 by using heat shrinkable tubing. If less than four cables are required for the load circuits, the unused recesses should be plugged with moisture-proof plugs.

The metallic housing 146, which is preferably formed of a non-corrosive material, such as cast iron, is then threadably engaged with the threads 144 on the outer surface of housing 66, and turned to advance it onto the housing until the top of the housing 146 is at the desired elevation relative to the grade level 148. A

metallic grounding strap 264 is connected to the metallic housing 146 and also to the metallic angle 162, as illustrated in FIG. 5. The grounding strap 264 may be advantageously connected to housing 146 by providing a tapped opening in the housing for receiving a bolt 266 which may be tightened to securely fasten the grounding strap 264 to the housing 146. The other end of the strap 264 may be independently grounded, if desired.

The fused removable member 64 may then be inserted into chamber 70, to connect the plurality of load circuits to the source of electrical potential via the current limiting fuse 220. The hasp 150 may then be pivoted to direct the eye bolt 256 through the slot 152 in the hasp, and a lock 268 may be looped through the opening in the eye bolt 256 and locked to prevent unauthorized removal of the element 64. An additional inner seal may be provided about the upper end of housing 66, which will prevent water from accumulating and freezing about the hasp 150 and eye bolt 256. The inner seal may be in the form of a tubular insulating housing 270, formed of a material such as hard rubber, which has an inside diameter sized to snugly fit over the first end of the housing 66. A gasket member 272 may be disposed between the outside diameter of the housing 66 and the inside diameter of the tubular inner housing 270. An insulating cap member 274 is then disposed to seal the upper open end of the inner housing 270.

A cover 276 is then disposed to seal the opening to the metallic outer housing 146, with a gasket member 278 being disposed between the cover 276 and the housing 146 to provide a hermetic seal. Cover 276 may be of the type which has a plurality of outwardly extending tangs which cooperate with flanges disposed on the housing, to force the cover against the gasket 278 when the cover 276 is rotated to mesh the outwardly extending tangs with the cooperative flanges on the metallic housing. The earth removed from the trench may then be disposed about the electrical connector 60.

The electrical connector 60 may be used as a sectionalizing switch, such as for switch 18 shown in FIG. I, by replacing the current limiting fuse 220 with a solid metallic bar 280, as shown in FIG. 8. The resulting removable portion is given the reference numeral 64, and like elements in FIGS. 7 and 8 are indicated with like reference numerals. A retainer plate 238, such as shown in FIG. 7A, may be used to hold the garter spring 234, and a similar plate 238' may be disposed adjacent contact 258, as a guide in directing contact 258 into proper engagement with the contact member 108. In this instance, one of the cables of the electrical distribution loop would be plugged into one of the bottom tubular extensions, and one would be plugged into one of the top tubular extensions, with the remaining tubular extensions being sealed with moisture-proof plugs.

When it is necessary for maintenance personnel to work on the load circuits, the load circuits may be grounded by using a removable grounding element 290, which is shown in FIG. 9. Grounding element 290 includes a garter spring 232 and inverted cap type retaining member 234, as hereinbefore described relative to FIG. 7, but instead of using an insulating rod 250 for an operating shaft, a metallic rod member 292 is connected to contact 232 and to the eye bolt 256. Eye bolt 256 may be grounded, as indicated, and an insulating rod 298 may be secured to contact 232 with a threaded pin 296, which pin is also threadably engaged with the metallic rod 292. A retainer cap 294 may be used to help support the garter spring 232. Thus, when it is desired to take the load circuits out of service for maintenance reasons, the removable element 250 shown in FIG. 7 may be removed, and the removable element 290 shown in FIG. 9 inserted in order to positively insure that the circuits being maintained are grounded.

While the lower cooperative contact members of the removable element 64 and housing 66 are illustrated with the female contact fixed to the housing 66 and the male contact fixed-to the removable element 64, it is to be understood that this structure may be modified such that the male contact is fixed to the housing 66, and the female contact is carried by the removable connecting element 64. In this instance, the arc extinguishing members would also exchange positions, with the insulating tubular sleeve member being carried by the removable element 64, and the snuffer rod being mounted on the upwardly extending end of the male element, fixed to the insulating housing 66.

In summary, there has been disclosed a new and im proved electrical connector for interconnecting an electrical distribution loop with a plurality of electrical circuits via a removable connecting element, such as a current limiting fuse. The new and improved electrical connector utilizes all plug-in connectors, connecting both the source of electrical potential and the load circuits to the connector with plug-in connections, without incurring a cost penalty that ordinarily would accompany the use of the plug-in concept. This advantageous result is obtained by a new and improved insulating housing for the electrical connector, in which the plug-in receptacles are integrally formed with the main body portion of the housing, and also due to new and improved first and second spaced contact structures which are carried by and embedded in the housing, which contact structures may be manufactured for a relatively low cost, but which provide extremely effective and reliable electrical joints when coupled with the contacts of the removable element. The first contact structure includes a U-shaped metallic member with three contact members attached and extending outwardly therefrom, and the second contact structure is a metallic tube with two metallic rods or pins attached thereto, with these contact structures providing the male contacts of fixed plug-in receptacles, and a contact which cooperates with the lower contact carried by the removable element 64.

Further, the new and improved electrical connector has load-break' capability, making it unnecessary to utilize auxiliary switches, which would otherwise be required prior to closing and opening the electrical connector. Also, a current limiting fuse is provided which protects the electrical distribution loop against short circuits in the cables, transformers and connected loads, which are connected to the electrical connector.

The disclosed electrical connector may also be used as a sectionalizing switch; and, by using an auxiliary removable element, the load circuit may be quickly and easily grounded when maintenance personnel desire to take the load circuits out of service for maintenance purposes.

We claim as our invention:

1. An electrical connector for interconnecting an electrical distribution loop with a plurality of electrical circuits via a removable connecting element, comprisan insulating housing formed of a resin system, in-

cluding a substantially cylindrical main body portion which defines a chamber having open and closed ends, first and second substantially tubular portions which extend outwardly from the main body portion near the closed end of the chamber, and a plurality of additional substantially tubular portions axially spaced from the first and second tubular portions, which also extend outwardly from the main body portion, said first and second and said plurality of additional substantially tubular portions each defining a recess having an open and a closed end,

first contact means carried by said insulating housing, including first, second and third interconnected contact members, said first contact member extending coaxially into said chamber through its closed end, and said second and third contact members extending coaxially into the recesses of said first and second substantially tubular portions, respectively, through their closed ends,

second contact means carried by said insulating housing, axially spaced from said first contact means, said second contact means including a tubular contact member disposed coaxially with the chamber of the insulating housing, having an inner surface which is accessible from within the chamber, and a plurality of contact members fixed to said tubular contact member which extend into the recesses of said plurality of additional substantially tubular portions, respectively, through the closed ends of the recesses,

means removably disposed in the chamber of said insulating housing having first and second spaced contact assemblies, and means electrically interconnecting said first and second spaced contact assemblies, said first and second contact assemblies engaging the first contact member of said first contact means, and the inside surface of the tubular contact member of said second contact means, respectively,

a first resilient, electrically conductive tubular member having first and second ends, disposed in each of said first and second and additional plurality of substantially tubular portions of said insulating housing, with the first end of the first resilient electrically conductive tubular member starting at the closed end of its associated recess, and surrounding the contact member which extends into the recess,

whereby the first and second substantially tubular portions of said housing are adapted to receive plug-in connectors connected to the electrical distribution loop, and the additional plurality of substantially tubular portions of said housing are adapted to receive plug-in connectors connected to the electrical circuits to be connected to the electrical distribution loop via said means removably disposed in the chamber of said insulating housing. 2. The electrical connector of claim 1 including an electrically conductive coating disposed on the outer surface of the insulating housing.

3. The electrical connector of claim 1 wherein the outer surfaces of each of the first resilient electrically conductive tubular members are bonded to the insulating housing.

4. The electrical connector of claim 1 including a second tubular resilient member having first and second ends disposed in each of the recesses defined by the first and second and additional substantially tubular portions of the insulating housing, with its first end overlapping the second end of the first resilient member to provide a seal, and its second end starting adjacent to the open end of the recess.

5. The electrical connector of claim 4 wherein the second tubular resilient member includes an electrically conductive portion starting at its second end and an insulating portion starting at its first end, with the electrically conductive insulating portions joining intermediate the first and second ends.

6. The electrical connector of claim 5 including an electrically conductive coating disposed on the outside surface of the insulating housing, with the electrically conductive portion of each of the second tubular resilient members contacting said electrically conductive coating.

7. The electrical connector of claim 1 wherein the means removably disposed in the chamber of the insulating housing includes a current limiting fuse.

8. The electrical connector of claim 1 wherein the plurality of contact members fixed to the tubular contact of the second contact means include at least one elongated metallic member having first and second ends, with an intermediate portion of the elongated metallic member being fixed to the outer surface of the tubular contact, and with the first and second ends of the elongated metallic member extending into different recesses.

9. The electrical connector of claim 8 including a second elongated metallic member having first and second ends, with an intermediate portion of the second metallic member being fixed to the outer surface of the tubular contact, and with its first and second ends extending into different recesses.

10. The electrical connector of claim 1 wherein the means removably disposed in the chamber of the insulating housing seals the open end of the chamber.

11. The electrical connector of claim 1 including a cylindrical metallic housing having first and second open ends, with the second open end adjustably disposed about the insulating housing, and including cover means for closing the first open end of the cylindrical metallic housing.

12. The electrical connector of claim 11 including an intermediate housing of insulating material disposed within the cylindrical metallic housing, which encloses and seals the open end of the insulating housing.

13. The electrical connector of claim 1 including first and second arc extinguishing members carried by the insulating housing and means removably disposed in the chamber of the insulating housing, respectively,

.8, adapted to engage the tubular contact member of the second contact means, and including an electrically conductive shaft member connected to said single contact, with said electrically conductive shaft member being accessible external to the electrical connector, enabling it to be visibly connected to ground. 

1. An electrical connector for interconnecting an electrical distribution loop with a plurality of electrical circuits via a removable connecting element, comprising: an insulating housing formed of a resin system, including a substantially cylindrical main body portion which defines a chamber having open and closed ends, first and second substantially tubular portions which extend outwardly from the main body portion near the closed end of the chamber, and a plurality of additional substantially tubular portions axially spaced from the first and second tubular portions, which also extend outwardly from the main body portion, said first and second and said plurality of additional substantially tubular portions each defining a recess having an open and a closed end, first contact means carried by said insulating housing, including first, second and third interconnected contact members, said first contact member extending coaxially into said chamber through its closed end, and said second and third contact members extending coaxially into the recesses of said first and second substantially tubular portions, respectively, through their closed ends, second contact means carried by said insulating housing, axially spaced from said first contact means, said second contact means including a tubular contact member disposed coaxially with the chamber of the insulating housing, having an inner surface which is accessible from within the chamber, and a plurality of contact members fixed to said tubular contact member which extend into the recesses of said plurality of additional substantially tubular portions, respectively, through the closed ends of the recesses, means removably disposed in the chamber of said insulating housing having first and second spaced contact assemblies, and means electrically interconnecting said first and second spaced contact assemblies, said first and second contact assemblies engaging the first contact member of said first contact means, and the inside surface of the tubular contact member of said second contact means, respectively, a first resilient, electrically conductive tubular member having first and second ends, disposed in each of said first and second and additional plurality of substantially tubular portions of said insulating housing, with the first end of the first resilient electrically conductive tubular member starting at the closed end of its associated recess, and surrounding the contact member which extends into the recess, whereby the first and second substantially tubular portions of said housing are adapted to receive plug-in connectors connected to the electrical distribution loop, and the additional plurality of substantially tubular portions of said housing are adapted to receive plug-in connectors connected to the electrical circuits to be connected to the electrical distribution loop via said means removably disposed in the chamber of said insulating housing.
 2. The electrical connector of claim 1 including an electrically conductive coating disposed on the outer surface of the insulating housing.
 3. The electrical connector of claim 1 wherein the outer surfaces of each of the first resilient electrically conductive tubular members are bonded to the insulating housing.
 4. The electrical connector of claim 1 including a second tubular resilient member having first and second ends disposed in each of the recesses defined by the first and second and additional substantially tubular portions of the insulating housing, with its first end overlapping the second end of the first resilient member to provide a seal, and its second end starting adjacent to the open end of the recess.
 5. The electrical connector of claim 4 wherein the second tubular resilient member includes an electrically conductive portion starting at its second end and an insulating portion starting at its first end, with the electrically conductive insulating portions joining intermediate the first and second ends.
 6. The electrical connector of claim 5 including an electrically conductive coating disposed on the outside surface of the insulating housing, with the electrically conductive portion of each of the second tubular resilient members contacting said electrically conductive coating.
 7. The electrical connector of claim 1 wherein the means removably disposed in the chamber of the insulating housing includes a current limiting fuse.
 8. The electrical connector of claim 1 wherein the plurality of contact members fixed to the tubular contact of the second contact means include at least one elongated metallic member having first and second ends, with an intermediate portion of the elongated metallic member being fixed to the outer surface of the tubular contact, and with the first and second ends of the elongated metallic member extending into different recesses.
 9. The electrical connector of claim 8 including a second elongated metallic member having first and second ends, with an intermediate portion of the second metallic member being fixed to the outer surface of the tubular contact, and with its first and second ends extending into different recesses.
 10. The electrical connector of claim 1 wherein the means removably disposed in the chamber of the insulating housing seals the open end of the chamber.
 11. The electrical connector of claim 1 including a cylindrical metallic housing having first and second open ends, with the second open end adjustably disposed about the insulating housing, and including cover means for closing the first open end of the cylindrical metallic housing.
 12. The electrical connector of claim 11 including an intermediate housing of insulating material disposed within the cylindrical metallic housing, which encloses and seals the open end of the insulating housing.
 13. The electrical connector of claim 1 including first and second arc extinguishing members carried by the insulating housing and means removably disposed in the chamber of the insulating housing, respectively, which are disposed to confine and extinguish an arc formed between the first contact member of the first contact means and the first contact assembly of the means removably disposed in the chamber of the insulating housing.
 14. The electrical connector of claim 1 including an auxiliary removable element having a single contact adapted to engage the tubular contact member of the second contact means, and including an electrically conductive shaft member connected to said single contact, with said electrically conductive shaft member being accessible external to the electrical connector, enabling it to be visibly connected to ground. 